One task · many agents · one receipt
Not a chat window. steamtrain runs Claude Code, OpenCode, Codex, Cursor and Amp as managed subprocesses and drives them through declarative, parallel workflows — all streamed live, with real dollar and token costs on every step.
Fan a task out across models, cross-check the results, gate on what passed, and merge the verified changes back into your checkout. No copy-pasting between terminals.
steamtrain spawns the real claude, opencode, codex, agent, agy, kimi and amp CLIs — no stubs — and maps each one's streaming output onto a single normalized event model. Mix agents freely in one workflow.
Phases built from a few standard blocks: distributor, worker, consolidator, gate. Steps are dependency-scheduled — each starts the moment its inputs are ready, in parallel with everything unrelated.
Every agent step runs in its own isolated git worktree, so parallel agents never trample each other or your working copy. Apply is pre-checked and all-or-nothing; the merge happens in a throwaway staging worktree.
Each run is saved as one JSON record — the full phase → step tree with status, output, duration, cost and gate results. Re-running resumes from an on-disk cache instead of paying for completed steps again.
Bundled workflow · mainline
A planner splits your prompt into independent streams; each stream is implemented and review/fix/test-looped in its own worktree, in parallel; an agent merges the streams; the merged result gets one more review/fix/test pass; a PR opens.
Every out-of-scope bug anyone noticed along the way gets filed as a GitHub issue instead of silently dropped or scope-creeping the task.
$ steamtrain workflow run mainline \
--input "add rate limiting to /upload"
The terminal side
It opens on a workflow picker and streams the phase → step tree live. Enter runs, ↑/↓ inspects a step's output, Tab cycles workspace presets, Esc cancels. Start a run here, attach from the app — or the other way round.
Take a lap first if you like — the bundled tour workflow runs the whole engine for $0, with no agent, no API key and no credit.
Desktop app
Download for macOSCLI & TUI